The present invention relates generally to a metallic hollow golf club head, and specifically to the placement of a cup shaped front section having a wing element extending into the heel/skirt portion of the club body. The invention is also directed to an improved split hosel design.
Golf club xe2x80x9cmetal woodsxe2x80x9d, were originally manufactured primarily by casting of durable metals such as stainless steel, aluminum, beryllium copper, etc. into a unitary structure comprising of a metal body, face and hosel. As technology progressed it became more desirable to strengthen the face of the club, and usually this was achieved by using titanium material.
With a high percentage of amateur golfers constantly searching for more distance on their drives, the golf industry has responded by providing golf clubs specifically designed with distance in mind. The head sizes have increased which allows for the club to possess a higher moment of inertia, which translates to a greater ability to resist twisting on off-center hits. However, as a wood head becomes larger, its center of gravity will be moved back away from the face resulting in hits flying higher than expected. Reducing the lofts of larger head clubs is one way to compensate for this. Also with the larger heads, the center of gravity is moved further away from the axis that is created by the intersection of the hosel with the sole plate. This can cause these large head clubs to remain open on contact, thereby inducing a xe2x80x9cslicexe2x80x9d effect (in the case of a right-handed golfer, the ball deviates to the right). Offsetting the head and incorporating a hook face angle can help compensate for this by xe2x80x9csquaringxe2x80x9d the face at impact, but often more is required to eliminate the xe2x80x9cslicexe2x80x9d tendency.
The technological breakthrough in recent years towards providing the average golfer with more distance by making club heads larger, has been to keep the weight constant or even lighter, by casting consistently thinner shell thickness and going to lighter materials such as titanium. Also the face of the clubs have been steadily becoming extremely thin. The thinner face will maximize what is known as the Coefficient of Restitution (COR), which means that the more the face rebounds upon impact, the more energy that may be imparted to the ball, thereby increasing distance. In order to make the faces thinner, manufacturers have moved to forged or stamped metal faces which are stronger, in most cases, than those that are cast. Common practice is to integrate the forged or stamped metal face by welding it to the body at the sole and crown transitions. These transitions are the points on the club head that absorb the greatest amount of stresses as the club strikes the ball. Therefore, it is very desirable to provide a method for attaching the impact face portion to the body of the club head without sacrificing any COR (Coefficient of Restitution) value in the club.
In accordance with one aspect of the invention, a metal wood golf club head is provided which includes a hollow body having a stamped metal cup-shaped, front section welded to it. The body is preferably cast as a single member and includes a sole portion, a crown portion, a toe portion that extends into the impact face of the front section, a heel portion, a skirt portion, and split hosel elements, upper and lower, all of which define a cavity therein. The cup-shaped, front section forms a substantial portion of the impact face of the club, and has a wing element extending around and beyond the upper hosel element and into the body at the heel/skirt area of the club. In addition to the face and wing element, the front section comprises an upper lateral extension that engages the crown portion and a lower lateral extension that engages the sole portion.
In the invention, the hosel elements are preferably cast as an integral part of the body. This allows weight that is normally needed to support the hosel, to be used elsewhere for optimum ball flight.
The present invention further provides for a section of the impact face to be cast as part of the toe portion of the body, thereby removing welding procedures from this area and improving the ease of polishing and buffing of the toe. Providing the toe portion of the impact face to be cast with the body increases stability of the cast body during manufacturing and insures minimum deformation of the aesthetically critical toe area.
Since a stamped plate made of beta-titanium generally exhibits better strength and ductility properties than cast titanium, it is preferable to use it as a substantial portion of the impact face of the front section. It is preferred that in the joining of the front section to the body, the welding be removed from the crown/face and sole/face transition seams, which are points of critical stress. The present invention provides for these welds to be done a distance away from the transition seams, thereby keeping the thickness at the transitions much thinner than if welds were present. This increases the structural integrity of the club head and also achieves maximum allowable COR values.
The present invention also provides for a split hosel design. Upper and lower tubular hosel elements are preferably manufactured as part of the cast body. These elements are preferably a reduction in weight from a full hosel that extends from the crown to the sole. The upper hosel element preferably extends from the crown of the club head and the lower hosel element is preferably integral with the inner surface of the sole plate. The lower hosel element has a boss member disposed thereon to provide support for the golf club shaft at one of a plurality of pre-determined positions. By positioning the shaft within the boss member in this manner, the lie of the golf club may be set at a pre-selected angle without any change to the master casting. To aid in the accommodation of different shaft angles, the upper hosel element is bendable to a slight extent.
The selection of club face angles from closed-face to open-faced can be achieved by the positioning of the boss member relative to the impact face, close to the face would create a more open-faced club angle, or conversely, away from the face, which would yield a more closed-face club angle.
The front section is preferably formed from a single stamped sheet metal plate, preferably of varied thickness, and being capable of being bent into a cup-shape. Each thickness area correlates to a thickness requirement of a corresponding part of the front section. The impact face, upper and lower lateral extensions, and wing element all having their own thickness requirements.